[R] Multiple logical operations in a subscript

[(Ted Harding)]

On 19-Sep-08 16:03:45, Greg Snow wrote:
> Peter showed you the %in% operator, you may also want to look at the
> subset, transform, with, and within functions for future use as ways to
> reduce the need to type the name of an object multiple times.
> 
> Hope this helps,

Let me add my perhaps very simple-minded suggestion. What I usually
do in such a situation is to define a working variable with a short name.
So, in the case of your example:

  dataframe$newvariable[data$oldvariable=="X" | "Y" | "Z"]<-"group1"

I would:

  Old<-data$oldvariable
  dataframe$newvariable[(Old=="X")|(Old=="Y")|(Old=="Z")] <- "group1"

which is what I take your intended meaning to be -- if so, then your
formulation of the condition is wrong, since

  data$oldvariable=="X" | "Y" | "Z"

will first (because of precedence rules -- see ?Syntax) evaluate
  data$oldvariable=="X""
(to TRUE or FALSE), and then try to OR ("|") this with the values
of "X and "Z". Since these are character strings, the operation is
not permitted:

  "Y"|"Z"
  Error in "Y" | "Z" : 
    operations are possible only for numeric or logical types

On the other hand:

  1|(-2)|(3.14159)
  [1] TRUE

Hoping this helps,
Ted.


>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
>> project.org] On Behalf Of Mark Na
>> Sent: Thursday, September 18, 2008 6:11 PM
>> To: R-help at stat.math.ethz.ch
>> Subject: [R] Multiple logical operations in a subscript
>>
>> Hello,
>>
>> I would like to select cases using multiple logical operations (e.g. X
>> or Y or Z) without having to repeat the dataframe$variable within the
>> subscript. My working code (with a single logical operator) currently
>> looks like this:
>>
>> dataframe$newvariable[data$oldvariable=="X"]<-"group1"
>>
>> I thought this next line of code might do what I wanted, but it
>> doesn't:
>>
>> dataframe$newvariable[data$oldvariable=="X" | "Y" | "Z"]<-"group1"
>>
>> I'd appreciate any suggestions. I've tried playing around with grep,
>> but
>> can't make it work.
>>
>> Thanks! Mark
>>
>> ______________________________________________
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>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-
>> guide.html
>> and provide commented, minimal, self-contained, reproducible code.
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

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E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
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Date: 19-Sep-08                                       Time: 17:28:20
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